Anti-carbamylated protein (Anti-CarP) antibodies are prevalent in indigenous North American (INA) patients with rheumatoid arthritis (RA) and are more common in first-degree relatives (FDR) vs controls. This according to a study of Anti-CarP IgG and anti-cyclic citrullinated protein antibodies (anti-CCP) in sera from 95 INA patients with RA, 109 of their unaffected FDR, and 85 healthy INA controls. Researchers found:

• Anti-CarP antibodies were more frequent in INA patients with RA than in INA FDR (44.3% vs 18.3%) or INA controls (4.7%).

• The anti-citrullinated protein antibodies (ACPA) score was higher in patients with anti-CCP+ve RA than in FDRs with anti-CCP+ve.

• The association with RA was strongest when all 3 autoantibodies (RF, anti-CCP, and anti-CarP) were present.

Citation: Koppejan H, Trouw LA, Soklove J, et al. Anti-carbamylated protein antibodies in rheumatoid arthritis, first-degree relatives and controls: Comparison to anti-citrullinated protein antibodies. [Published online ahead of print March 4, 2016]. Arthr Rheumatol.doi:10.1002/art.39664.